Integral longitudinal member for motor vehicles

ABSTRACT

Longitudinal members for motor vehicles may generally include a supporting element that is releasably connectable to an energy absorption mechanism. The supporting element may typically include a joining zone that can be used to secure the supporting element to one or more chassis or drive components of the motor vehicle. The supporting element and the energy absorption mechanism may be comprised of fiber-reinforced plastic. More specifically, the supporting element may be comprised of a plurality of length portions having different fiber orientations. For example, a first length portion may have fibers oriented substantially parallel to a horizontal longitudinal plane about which the supporting element is positioned, whereas a second length portion between the first length portion and the energy absorption mechanism may have intersecting fibers oriented oblique to the horizontal longitudinal plane.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Entry of International PatentApplication Serial Number PCT/EP2014/060407, filed May 21, 2014, whichclaims priority to German Patent Application No. DE 102013106073.0 filedJun. 12, 2013, the entire contents of both of which are incorporatedherein by reference.

FIELD

The present disclosure relates to motor vehicles and, more particularly,longitudinal members for motor vehicles that are capable of absorbingimpact energy.

BACKGROUND

Currently, vehicle front structures are predominantly designed to theeffect that they are substantially composed of metallic components inview of the supporting function and the impact energy absorption.Disadvantages of said structures include, in particular, the relativelyhigh weight and the complicated manufacturing, i.e. the blank, thedeformation and joining, and also the limited variability of the wallthicknesses in respect of the requirements regarding rigidity and crashperformance. Furthermore, repair following a collision proves highlycomplicated since, in the event of corresponding crash loads, the entirefront section structure may possibly need to be replaced as aconsequence of the energy absorption by deformation also reaching overthe entire part.

JP 2005-271872 A describes a longitudinal member for a motor vehicle,which is constructed from a supporting element and a tubular energyabsorption element, wherein the two elements are produced from fiberreinforced plastic. The supporting element has a length portion designedas a closed hollow profile and a length portion of substantiallyU-shaped design, and contains a supporting core made of foam. A hollowchamber is formed in the supporting core in the region of the closedhollow profile, said hollow chamber being connected to the hollowchamber defined by the tubular energy absorption element and serving, inthe event of a high crash load, to receive a part of the energyabsorption element that is slipped inward as a consequence of thedeformation. In addition, metal parts are embedded in the supportingelement in order to connect other body structure parts thereto. Thesupporting element and the energy absorption element are adhesivelybonded to each other.

In the case of the longitudinal member known from JP 2005-271872 A, itis in particular unsatisfactory that the repair of said longitudinalmember following a collision with a high crash load is scarcely possibleor at any rate is highly complicated because of the integrally bondedadhesive connection of supporting element and energy absorption element.

The present disclosure relates to a longitudinal member for a motorvehicle, in particular an electric vehicle, with an energy absorptionelement for absorbing impact energy, and a supporting element forsupporting chassis and/or drive components. The supporting element mayhave a joining zone for connection to at least one adjacent body part.Further, the energy absorption element and the supporting element may insome cases be produced from fiber reinforced plastic. Still further, thepresent disclosure is based on the object of providing a longitudinalmember that absorbs both crash loads and operating loads, in particularchassis loads, has a low weight, contributes to an improved structuralrigidity of the vehicle front or rear structure and is comparativelyeasy to repair.

This object is achieved according to the invention by a longitudinalmember with the features of claim 1. Preferred and advantageousrefinements of the longitudinal member according to the invention arespecified in the dependent claims which refer back to claim 1.

The longitudinal member according to the invention is characterized inthat the supporting element has length portions of differing fiberorientation, wherein one of the length portions contains reinforcingfibers running substantially parallel to a horizontal longitudinal planeof the longitudinal member, while a further length portion of thesupporting element, which length portion is located between the energyabsorption element and the first-mentioned length portion containsintersecting reinforcing fibers running obliquely with respect to thelongitudinal axis of the longitudinal member, and in that the energyabsorption element and the supporting element are connectable releasablyto each other.

By means of the length portions of different fiber orientation, there isan increase firstly in the flexural rigidity and secondly in thetorsional rigidity of the supporting element or longitudinal member,wherein the reinforcing fibers running substantially parallel to ahorizontal longitudinal plane of the longitudinal member serve, inaddition to improving the flexural rigidity, in particular also forabsorbing crash loads (impact loads). At the same time, the supportingelement of the longitudinal member according to the inventioncontributes considerably, by means of length portions thereof ofdifferent fiber orientation, to an improved structural rigidity of thevehicle front or rear structure. Furthermore, the longitudinal memberaccording to the invention, as a lightweight component produced fromfiber reinforced plastic, meets the requirement for a low componentweight. In addition, because of the releasable connection between energyabsorption element and supporting element, the longitudinal memberaccording to the invention is easy to repair. This is because the energyabsorption element can therefore be replaced by a new energy absorptionelement following a collision in which said energy absorption elementwas exposed to relatively low crash loads.

In an advantageous refinement of the longitudinal member according tothe invention, the supporting element has a fastening flange or afastening region for the releasable connection of the energy absorptionelement. The fastening flange or fastening region permits a reliableconnection of supporting element and energy absorption element, wherein,at the same time, a substantially uniform transmission of force from theenergy absorption element to the supporting element is ensured.Furthermore, the torsional rigidity of the supporting element or of thelongitudinal member is improved by the fastening flange or fasteningregion.

A further advantageous refinement of the longitudinal member accordingto the invention is characterized in that the energy absorption elementhas a sleeve-like end with a shoulder, into which the supporting elementis inserted or is insertable. This refinement facilitates theinstallation of the energy absorption element and contributes to aparticularly reliable connection of supporting element and energyabsorption element.

According to a further advantageous refinement of the longitudinalmember according to the invention, the energy absorption element of saidlongitudinal member has an integrated foam structure. By this means, thecrash load absorption capacity of the longitudinal member according tothe invention can be further improved.

In a further advantageous refinement of the longitudinal memberaccording to the invention, the energy absorption element has lengthportions of different wall thickness. The wall thickness of the energyabsorption element preferably decreases here continuously or in astepwise manner from the supporting element in the direction of that endof the energy absorption element which faces away from the supportingelement. By this means, the crash performance of the longitudinal memberaccording to the invention can be optimized.

Furthermore, the crash performance of the longitudinal member accordingto the invention can also be optimized if, according to a furtherpreferred refinement, the energy absorption element has length portionsof different cross-sectional shape, wherein said energy absorptionelement merges from a round cross-sectional profile into a substantiallyrectangular cross-sectional profile in the direction of the supportingelement.

In order to obtain a low component weight, in a further preferredrefinement of the longitudinal member according to the invention, thesupporting element of said longitudinal member is designed as acontinuous hollow body. The supporting element here is designed as aclosed hollow profile at least over a length portion, wherein theprofile cross section is preferably designed so as to be variable, i.e.different, over the longitudinal axis of the supporting element.

In order to be able to introduce operating loads, such as, for example,chassis loads, over a large area into the supporting element and inorder to be able further to reduce in particular the wall thickness andtherefore the weight of the longitudinal member or of the vehicle as awhole by means of the introduction of load over a large area, accordingto a further preferred refinement of the invention the supportingelement is provided with a bracket for the connection of a chassis ordrive component.

It is also advantageous for the lightweight construction of thelongitudinal member according to the invention if, according to afurther preferred refinement, the supporting element has reinforcingribs arranged on the inside.

A further advantageous refinement of the longitudinal member accordingto the invention is characterized in that the joining zone for theconnection of the supporting element to at least one adjacent body partis of U-shaped design. By this means, in particular, the structuralrigidity of a front section region and the absorption of crash loads, inparticular the distribution of the latter to adjacent body parts, suchas, for example, the end wall (splash wall) separating the passengercompartment from the engine compartment, can be optimized. In thisconnection, in a further preferred refinement of the invention, theU-shaped joining zone has a clear width which is at least two times,preferably at least 2.5 times the cross-sectional width of thesupporting element at the transition thereof to the energy absorptionelement. In this case, the longitudinal member according to theinvention can define a part of the end wall, in particular a part of thefootwell wall, in the front section, wherein a further reduction in thevehicle weight can be achieved by means of this additional function.

According to a further advantageous refinement of the longitudinalmember according to the invention, the supporting element and/or theenergy absorption element have/has at least one rectilinear marker line.The latter can be used for calibrating (aligning) the longitudinalmember or the elements thereof and therefore serves for qualityassurance or functional optimization.

The invention is explained in more detail below with reference to adrawing which illustrates a plurality of exemplary embodiments and inwhich, schematically:

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an example longitudinal member for usein a motor vehicle.

FIG. 2 is a perspective view of the example longitudinal member of FIG.1 wherein an example energy absorption element is shown to be detachedfrom an example supporting element.

FIG. 3 is a perspective view of the example supporting element of theexample longitudinal member of FIG. 2 with an example bracket attachedthereto for connection to a chassis or drive component.

FIG. 4 is a perspective view of an example supporting element of alongitudinal member.

FIG. 5 is another perspective view of an example supporting element of alongitudinal member.

FIG. 6 is a perspective view of an example energy absorption elementwith an example integrated foam structure.

DETAILED DESCRIPTION

Although certain example methods and apparatus have been describedherein, the scope of coverage of this patent is not limited thereto. Onthe contrary, this patent covers all methods, apparatus, and articles ofmanufacture fairly falling within the scope of the appended claimseither literally or under the doctrine of equivalents.

The longitudinal member 1 illustrated in the drawing is determined inparticular for fitting into a vehicle front structure. Said longitudinalmember is constructed from a supporting element 1.1 for supporting atleast one chassis or drive component (not shown) and from an energyabsorption element 1.2 for absorbing impact energy (crash loads),wherein the supporting element 1.1 has a joining zone 1.3 for theconnection of the longitudinal member 1 to at least one adjacent bodypart, such as, for example, a vehicle floor plate, a splash wall and/oran A pillar.

The supporting element 1.1 and the energy absorption element 1.2 areboth produced from fiber reinforced plastic. The fiber reinforcedplastic contains a reinforcing textile which is preferably formed from awoven fabric and/or braid made of glass or carbon fibers and is embeddedinto a matrix material made from thermoplastic or thermosetting plastic.One or more layers of the reinforcing textile can be embedded in thewall of the supporting element 1.1 or energy absorption element 1.2. Thewall thickness of the supporting element 1.1 or energy absorptionelement 1.2 lies, for example, within the range of approx. 2 to 6 mm.

The energy absorption element 1.2 is connected releasably to thesupporting element 1.1. The supporting element 1.1 is designed as acontinuous hollow body. Said supporting element has length portions ofdifferent cross-sectional shape. The length portion 1.11 connected tothe energy absorption element 1.2 has a closed, substantiallyrectangular cross-sectional shape (profile shape) and merges into awidth- and height-extended length portion 1.12 which has a recess(niche-shaped opening) 1.13 on the upper side thereof and is thereforeof U-shaped design in particular in the region of the joining zone 1.3.An upwardly protruding collar 1.14 is integrally formed on the recess1.13. The collar 1.14 is preferably formed continuously and extends fromthe one limb end 1.31 of the U-shaped joining zone 1.3 as far as theother limb end 1.32 thereof. Furthermore, a connection or reinforcingrib 1.15 can be integrally formed on the outside of the supportingelement 1.1, in particular adjacent to the joining zone 1.13.

The supporting element 1.1 has a fastening region 1.18 on the end sidethereof facing the energy absorption element 1.2. A sleeve-like end1.21, into which the supporting element 1.1 is inserted or isinsertable, is formed on the energy absorption element 1.2. Thesleeve-like end 1.21 here has, on the inside, a shoulder (stop) whichlimits the insertion depths of the supporting element 1.1. Thepreferably releasable connection is undertaken in the overlapping regionof the sleeve-like end 1.21 and of the fastening region 1.18.

Alternatively, in the case of another refinement of the energyabsorption element (not illustrated here in FIGS. 1 to 3), theconnection to the supporting element 1 can also be undertaken via afastening flange 1.16 which is directed radially inward (cf. FIGS. 4 and5).

The joining zones 1.18 and/or 1.3 or 1.16 and/or 1.3 of the longitudinalmember 1 according to the invention are designed in such a manner thatsaid longitudinal member can be joined both releasably and alsononreleasably. In order to permit or to facilitate a replacement of theenergy absorption element 1.2 in the event of repair, the energyabsorption element 1.2 and the supporting element 1.1 are preferablyconnected releasably to each other.

Furthermore, one or more brackets 1.4, angle brackets or the like can beattached, preferably laterally, to the supporting element 1.1, inparticular can be integrally formed thereon or fitted releasablythereto, and to which chassis components (not shown), for example atransverse link, can be fitted.

The energy absorption element 1.2 is of substantially tubular design. Itpreferably has a closed cross-sectional shape. The cross-sectional shapechanges, however, over the length of the energy absorption element 1.2.The connecting portion with the sleeve-like end 1.21 has a substantiallyrectangular cross-sectional profile in a manner corresponding to theadjoining length portion 1.11 of the supporting element 1.1. The energyabsorption element 1.2 merges in the direction of the end thereof facingaway from the supporting element 1.1 into a round cross-sectionalprofile 1.22. The outside diameter of the round cross-sectional profile1.22 is significantly smaller at the end to be connected to a bumper(not shown) or the like than the width or height of the rectangularcross-sectional profile at the opposite end 1.21 which is connected oris connectable to the supporting element.

According to the invention, the supporting element 1.1 has lengthportions 1.11, 1.12 of different fiber orientation, wherein one (1.12)of the length portions contains reinforcing fibers running substantiallyparallel to a horizontal longitudinal plane of the longitudinal member 1or parallel to the longitudinal axis of the vehicle, while a furtherlength portion (1.11) of the supporting element 1.1, which lengthportion is located between the energy absorption element 1.2 and thefirst-mentioned length portion 1.12, contains intersecting reinforcingfibers running obliquely with respect to the longitudinal axis of thelongitudinal member 1. This is indicated schematically in FIG. 4 byintersecting lines L1 and by lines L2 running parallel to one another.The intersecting lines L1 correspond to reinforcing fibers made of glassfibers or preferably carbon fibers, which run obliquely with respect tothe longitudinal axis of the longitudinal member 1, for example,substantially at an angle of approx. +/−45°. Such a fiber orientationcan be produced, for example, by braiding reinforcing threads producedfrom reinforcing fibers. The reinforcing fibers running substantiallyparallel to a horizontal longitudinal plane of the longitudinal member 1or parallel to the longitudinal axis of the vehicle can be produced, forexample, by corresponding laying of reinforcing threads (L2) producedfrom reinforcing fibers.

The intersecting reinforcing fibers (L1) running obliquely with respectto the longitudinal axis of the longitudinal member 1, for example at anangle of approx. +/−45° increase the torsional rigidity of thelongitudinal member 1. The reinforcing fibers (fiber layers L2), whichrun substantially parallel to a horizontal longitudinal plane of thelongitudinal member 1 or parallel to the longitudinal axis of thevehicle, serve to absorb crash loads and increase the flexural rigidityof the longitudinal member 1.

In order to further increase the rigidity of the longitudinal member 1,in particular the torsional rigidity thereof, the supporting element 1.1can also be provided with reinforcing ribs 1.17. The reinforcing ribs1.17 are preferably formed on the inside of the supporting element 1.1,specifically in the length portion 1.11 having the closed rectangularcross-sectional profile (cf. FIGS. 2 and 3).

In the exemplary embodiment illustrated in FIG. 5, the supportingelement 1.1 has, on the outside, two rectilinear marker lines 1.5 whichtogether enclose an angle, preferably an angle of 90°. Said markers 1.5can be used for calibrating (aligning) the longitudinal member 1 or theelements 1.1, 1.2 thereof. They therefore serve for quality assurance orfunctional optimization.

The design of the longitudinal member 1 according to the invention isnot restricted to the exemplary embodiments illustrated in the drawing.On the contrary, numerous variants which are also used in aconfiguration, differing from the drawing, of the invention specified inthe appended claims, are conceivable. For example, the energy absorptionelement 1.2 can contain an integrated foam structure 1.50 as shown inFIG. 6 and/or can have length portions of different wall thickness.Furthermore, a longitudinal member 1 according to the invention can alsoserve for the separation of a wet region and dry region of the vehicleconcerned. In particular, the longitudinal member 1 according to theinvention can bound a footwell in the vehicle front structure.

What is claimed is:
 1. A longitudinal member for a motor vehicle whereinthe longitudinal member is oriented along a longitudinal axis in ahorizontal longitudinal plane, the longitudinal member comprising: asupporting element for supporting chassis and/or drive components,wherein the supporting element includes a joining zone connectable to atleast one adjacent body part of the motor vehicle, wherein thesupporting element is oriented along the longitudinal axis in thehorizontal longitudinal plane; and an energy absorption mechanismreleasably connectable to the supporting element and configured toabsorb impact energy, wherein the energy absorption mechanism and thesupporting element are comprised of fiber-reinforced plastic, whereinthe supporting element has a plurality of length portions with differingfiber orientations, wherein a first length portion of the plurality oflength portions includes reinforcing fibers that are substantiallyparallel to the horizontal longitudinal plane, wherein a second lengthportion of the plurality of length portions is located between theenergy absorption mechanism and the first length portion and includesintersecting reinforcing fibers that are oblique to the longitudinalaxis.
 2. The longitudinal member of claim 1 wherein the supportingelement comprises a fastening flange or a fastening region forreleasably connecting the supporting element to the energy absorptionmechanism.
 3. The longitudinal member of claim 1 wherein the energyabsorption mechanism comprises a sleeve-like end with a shoulder intowhich the supporting element is insertable.
 4. The longitudinal memberof claim 1 wherein the energy absorption mechanism comprises anintegrated foam structure.
 5. The longitudinal member of claim 1 whereinthe energy absorption mechanism comprises a plurality of length portionswith differing wall thicknesses.
 6. The longitudinal member of claim 1wherein the energy absorption mechanism comprises a plurality of lengthportions having different cross-sectional shapes, wherein the energyabsorption mechanism transitions from a round cross-sectional profile ata first length portion to a substantially rectangular cross-sectionalprofile at a second length portion, with the second length portion beingmore proximate to the supporting member than the first length portion.7. The longitudinal member of claim 1 wherein the supporting elementcomprises a continuously hollow body.
 8. The longitudinal member ofclaim 1 wherein the supporting element comprises a bracket forconnection to the chassis and/or drive components.
 9. The longitudinalmember of claim 1 wherein the supporting element comprises an inside andan outside, wherein the inside of the supporting element comprisesreinforcing ribs.
 10. The longitudinal member of claim 1 wherein thejoining zone comprises a U-shaped design.
 11. The longitudinal member ofclaim 1 wherein the U-shaped design of the joining zone is at least twoand a half times as wide as a width of the supporting element at a pointwhere the supporting element connects to the energy absorptionmechanism.
 12. The longitudinal member of claim 1 wherein at least oneof the supporting element or the energy absorption mechanism includes arectilinear marker line.
 13. A longitudinal member for absorbing impactenergy in a motor vehicle, wherein the longitudinal member is orientedin a horizontal longitudinal plane, the longitudinal member comprising:a supporting element for supporting at least one of a chassis componentor a drive component, wherein the supporting element is connectable toat least one adjacent body part of the motor vehicle, with thesupporting element being oriented in the horizontal longitudinal plane;and an energy absorption mechanism releasably securable to thesupporting element, wherein the energy absorption mechanism and thesupporting element are comprised of fiber-reinforced plastic, whereinthe supporting element has a first length portion with reinforcingfibers that are substantially parallel to the horizontal longitudinalplane, wherein the supporting element has a second length portionlocated between the energy absorption mechanism and the first lengthportion, with the second length portion including intersectingreinforcing fibers that are oblique to the horizontal longitudinalplane.